Actually, there are programs kinda like this already for DBC:
Matedit, WorldMaker, 3dMapEditor... The difference is they have a user interface that is based on mouse commands and GUI interaction mostly.
One could for instance, make a series of functions that were bundled commands, and create a sort of script language. Then, split the screen, and have one side be the inputs for the user script commands, and the other side the visual result. Instead of using the mouse to click and stretch an area to make a cube as in MagicWorld, the interface could be a script language. All the inputs are saved in memory (or as a file) in the form of the script language and when the edits are done, the script is broken back down to DBC code and saved as a file.
Enjoy your day.